The present invention relates to a closure for injecting a material into a hole. More particularly it relates to a tubular one-way closure for injecting synthetic plastic foam material in a drill hole, which closure comprises a throttle channel through which a material is to be injected, a central tube and an elastic tubular sealing member mounted on said central tube.
Closures of this general type have already been proposed. In such a closure an annular internal recess is provided between the central tube and the elastic tubular member, which recess communicates with a through hole in the central tube. The above mentioned internal recess is filled with components of synthetic plastic material, the volume of the thus-filled internal recess is increased and the elastic tubular member is pressed against an inner surface of the drill hole so as to seal the same.
This construction of the closure possesses some disadvantages.
The elastic tubular member serves as the only means for both sealing of the drill hole and anchoring of the closure in the drill hole. In order to perform a sealing action the sealing member must be constituted of a highly elastic material, and therefore such member can not ensure a sufficient anchoring action, which in turn permits undesirable slippage of the closure relative to the inner surface of the drill hole.
It is also possible in this construction that during the filling of the ring-shaped recess only one of the components of the synthetic material enters the recess, with the result that a sufficient expansion of the elastic tubular member can not be obtained. After the injection into a drill hole, the mixing chamber of a pressure pump used for the purpose is cleaned out to remove the synthetic material and prevent hardening of the same in the mixing chamber. For injecting into the next drill hole, the mixing chamber and feeding conduits must be cleaned of said component before dispensing a multicomponent mixture. This moment of time can not be easily fixed which also causes certain difficulties.
Furthermore, pressure produced by foam material and exerted on the elastic member is not sufficient to anchor the closure in a drill hole having a smooth internal surface. This can also result in slippage of the closure relative to the internal surface of the drill hole.
A closure is also known which is glued in the drill hole with synthetic plastic foam material by means of a special operation. This has the disadvantage that an additional loss of time and a separate operation are required. The gluing is carried out in a zone adjacent to a mouth of the drill hole. However, it is desirable to anchor the closure at such a depth that the material to be injected will not be located adjacent an inlet part of the drill hole in the outer area of a longitudinal wall.
The above-mentioned constructions of the closure can be found, for example, in German Pat. Nos. 2,402,509 and 2,205,823.